Hey, figured this site might be a good place to ask about the One Piece video games. I live in Europe, so I can apparently pick up Unlimited Cruise SP/SP 2, One Piece Pirate Warriors 1 & 2, and later this month Romance Dawn.

Romance Dawn appears to be a turn-based RPG that follows the pre-time skip arcs of the manga (doesn't include any anime filler material I presume?). Pirate Warriors seems to basically be Dynasty Warriors with One Piece characters and it follows some of the post-time skip stuff (all of it? One saga?).

I'm guessing Pirate Warriors 2 covers a video game-only arc? Does it take place at a specific part of the main story?

Unlimited Cruise I have no idea on. I'm much more interested in Romance Dawn and Pirate Warriors because I want to retread through the story in game form, but if anyone can shed light on these games that'll be much appreciated!

Romance Dawn covers East Blue up to Marineford arcs, while Pirate Warriors 1 covers East Blue to Return to Sabaody arcs. Pirate Warriors 2 is like a retelling of all those arcs (mainly the latter ones), keeping all the characters but changing the story. Unlimited Cruise is a independent story, kind of like a dream where they re-fight past enemies/allies. Fair warning when playing these games they are not 100% faith full to the manga/anime, because then it would have to much text and not enough action (for a game).

There is never any filler in games, except Foxy is in an old Gamecube one that had him in there for multiplayer.

There is minor overlap in some of the arcs, like Drum Island. But PW2 is all "dream" versions so there are changes to the story so they are not the same as PW1. Also PW2 has more of the arcs that were missing, like Skypiea and Post Time skip, but again they are "dream" versions, so characters are present that should not have been, or the presence of dials are heavily influential out side of the Skypiea arc, and any combination of things. So your choice comes down to, do you want a re-telling of One Piece story, or a random match up of all characters (and a lot more characters) and plots through "dream" arcs. Also PW1 is regarded as the better of the two, mainly story wise and the fact that there were not mainly changes between 1 and 2 (meaning no improvements/advancements where there should have been, but that is the common issue in Dynasty Warrior games).

Doesn't Pirate Warriors 2 have more characters? It seems as far as adapting the manga story, Romance Dawn is the only one that does exactly what I want to the dot, so I'm not too bothered about what story PW1/2 have to offer.

I'm thinking I'll be wanting to get my hands on Pirate Warriors 2, Romance Dawn and Unlimited World RED (if it hits Europe), while skipping Pirate Warriors 1 and Unlimited Cruise SP (split into two overpriced parts = no buy).

PW2 does have more characters, but again it doesn't really follow the manga/anime. But from what I gather, yes Romance Dawn is the way to go for you. And for a hack/slash game with One Piece characters, you can't go wrong with either PW1/PW2. And I agree, Unlimited Cruise became very overpriced for what it is. I hope you enjoy Romance Dawn, it does a good job for a video game to cover the story faithfully. And PW2 has some very neat characters you can play as, so you should enjoy it gameplay wise.